Male sex increases the risk of autoimmunity but not type 1 diabetes.

OBJECTIVE The goal of this study was to explore the role of sex on the prevalence of autoantibodies, protective genetic subtypes, beta-cell function, and the incidence of type 1 diabetes in a population of first- and second-degree relatives of patients with type 1 diabetes (probands). We examined both the effect of the sex of the individual screened as well as the effect of the sex of the individual's proband on diabetes risk variables tested. RESEARCH DESIGN AND METHODS The Diabetes Prevention Trial-Type 1 has screened 93,188 relatives of type 1 diabetic patients from February 1994 to January 2002. After observing that more men than women were islet cell autoantibody (ICA) positive for the group as a whole, we further explored the role of sex by detailed analysis of variables in this population. RESULTS Our data suggest only an influence of sex on the type 1 diabetes disease process. After adjustment for race, age, and relationship to proband, male sex was associated with the appearance of autoimmunity, i.e., the presence of ICA and having two or more antibodies. There was no effect of sex on the presence of other autoantibodies, insulin secretion, results of oral glucose tolerance test, or development of diabetes. CONCLUSIONS Our finding that male sex conveys an independent increased risk for development of ICA and multiple antibodies, while at the same time finding no difference with respect to the development of diabetes, suggests that male relatives with the known risk factor of ICA are less likely than comparable female relatives to progress to overt disease, that the pathogenesis of type 1 diabetes among men is slower compared with women, or that women develop diabetes manifesting different antibody responses.